Compound engine



(No Model.)

3- Sheets-Sheet 1. H. D, DUNBAR.

coMPoUND ENGINE.

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(N6 Model.) 3 sheets-sheet 2.

H.D.DUNBAR.

COMPOUND ENGINE. H

No. 264.937. Ptentedsept. 26, 1882.I

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(No Model.) Y 3 Sheets-Sheet 3.

H. D. DU'NBAR.

A Go'MPoUND ENGINE. No. 264,937. 4 l Patented Sept. 26-l 1882.

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` UNITED STATES i PATENT OFFICE.

HENRY D. DUNBAR, OF NOR-TH HARTLAND, VERMONT COMPOUND ENGINE.

SPECIFICATION forming part of Letters Patent No. 264,937, dated September 26, 1882.

' Application tiled December29, 1881. (No model.)

providing two cylinders and two steam-chests,

or a single steam-chest with two steam-chambers arranged side by side, and connected with each other and with the cylinders by ports or passage-ways, and two pistons attached to a single rod common to both, whereby one or both said pistons may be actuated by live steam; o r one piston may be actuated by live steam and the other by exhaust-steam admitted through one of said chambers by a port controlled by a distributing-valve operated by the engineer, and I accomplish this by the mechanism hereinafter described, and illustrated in the accompanying drawings, in whch- `Figure I is a side view ot' two cylinders-arranged according to my invention. Fig. II is a plan view ot' the same, and connected with the saddle of a locomotive, as made in two parts bolted together.` Fig. III is a reverse plan view ot' a separate piece containing `the ports or passage-ways connecting one ofthe steam-chambers with olie ofthe cylinders.-

Fig. 1V is an end view of oneof the cylinders and the steam-chamber and saddle-piece connected therewith, in which are made a portion of the steam-passages. Fig. Vis a transverse vertical section at line A otl Fig. II. Fig. VI is a longitudinal vertical'section of the larger cylinder and its steam-chamber and valve at line E of Figs. II, IV, and V, and also a longitudinal section of the smaller cylinder and its steam-passages at line B of Figs. IV and V. Fig. VII is a vertical section of a portion of the cylinder and saddle-piece and steamchamber connected therewith at line C of Figs. II, IV, and V; and Fig. VIII is a vertical section of -the saddle-piece and steamchamber connected` therewith at line D of Figs. II, IV, and V, showing the arrangement of the ports forming communication between the smaller cylinder and the steam-chamber.

In the drawings12 represents one-half of a saddle-piece for a locomotive-en gine, two of which such pieces may be bolted together at 25 to form the saddle, and .l represents a cylinder, which may be cast in the saine piece with the saddle 12, and the upper side of this saddle, as 12, may be inadeplane and smooth tains another valve, as 9, also having a similar rod, as 8, attached.

A smaller cylinder, as 2, is secured to one end of the larger cylinder, as l, and a pistonrod, as 5, extendsthrough the larger cylinder and intothe smaller cylinder, witha piston, as 23, in thelarger cylinder, and also ai piston, as 24:, in the smaller cylinder, both secured to the said piston-rod, the pistons occupying the same relative positions each in its respective cylinder, and the axes of the piston-rod, pistons, and cylinders all being coincident.

A port or passage-way, as 13, is cast in the saddle, with an opening at one end, at the inner portion of the saddle, at a convenient point for the adj nstment of a steam-pi pe thereto, and with an opening at the other end, within the steam-chamber, as 4, as shown inidotted lines in Fig. II; and a port, as l4,`is made from the chamber 4 in the saddle and through the casting," as 26, opening into that end ot' the smaller cylinder adjacent to the large cylinder, and also a similar port, as 15,` extending to the opposite end of the smaller cylinder, as shown in Figs. VI and VIII. The "port, as 16, between the ports 14 and l5, ex-

tends down and out to one side and opens up into the valve-seat at 162 a little to one side of its opening I6, as shown in dotted lines in Fig. Il, and a port, as 21, extends. down bcneath the valve-seat of the chamber, as 4, and terminates in the port-opening 2l2 in the valveseat of the chamber, as 3.

The ports 20 and 19 communicate with the respective ends of the larger cylinder., as 1, in the ordinary manner, and as shown clearly in roo 2mes? t Fig. VI, and the exhaust-port, as 18, located in the valve-seat of the chamber, as 3, and between the openings 2O and 19, extends down and through the saddlepiece,as 12, and terminates in the exhaust-opening, as 182, at a convcnient point to receivepan exhaust-pipe.

A port or opening, as 17, is made in the valve-seat of the chamber, as 4, at one side of the port, as 162, which port, as 17, extends down and communicates with the exhaust port or passage 18, all as shown clearly in Figs. 1I and VII.

An ordinary slide-valve, as '7, may cover and operate in connection with the ports, as 18, 19, and 20, in the chamber, as 3, and any similar valve, as 11, may cover and operate in coni nection with the ports, as 14, 15, and 16, in the chamber, as-4.

l The openings or ports, as 162, 17, and 21, in the valve-seat of the chamber, as 4, are provided with, and the passage of steam `therethrough controlled-by, a distributing-valve,as 9, which may be of the ordinary slide-valve pattern; and the eXhaust-cavityin its lower side may be ot such length that when the valve is in the position shown in dotted lines in Fig. VII there may be communication between the'ports 17 and 21 through said exhaust-cavity, said ports then being only partially closed; but the valve, as 9, may `be-moved farther over in the direction of the dotted lines, or so as to completely close the said ports, as 17 and 21, from the chamber, as 4, in which case communication .between the steam-chambers 3 and 4 will be completely eut oft or closed. Of course the.

apertures in the ends of the cylinder through which the piston-rod operates are suitably packed, so that steam cannot pass from one cylinder to the other around the rod.

lf it is desired -to use live steam in both cylinders, the distributing-valve, as 9, is moved into the position show-n in full lines in Fig. VII, and with the slide-valves, as 7 and 11, in the position shown in Figs. VI and VIII, (as both valve-stems, as 6 and 10, may be attached to and moved by one and the same valve-rod',) the live steam may enter the pipe at 13 in the inner portionof the saddle-piece and pass into the chamber, as 4, through the port 13 in said chamber, and thence through the port, as 15, into that end of the smaller cylinder farthest from the larger one, and both pistons, with their common rod, as 5, are forced in a direction toward the opposite end of the cylinders, and theeXhaust-steam on the other side ofthe small piston, as 24, in the smaller cylinder, passes out through the port 14 and through the exhaust-cavity in the valve, as 11, into the port, as 16, out the port, as 162, through the exhaust-cavity in the distributing-valve, as 9, down through the port, as 17, and out through the exhaust-passage, as 18, and opening, as 182. At the same time that live steam passes in through the port, as l5, into the smaller cylinder, it also passes out from the steamchamber, as 4, through the port, as 2l, into the chamber, as 3, through the opening, as 212, and thence through the port, as 19, into the same end of the larger cylinder 1, so that at the same time the live steam in the smaller cylinder is exerting its force against the smaller piston, as 24, the live steam in the larger cylluder isexerting its force against the same side vof the larger piston, as 23, while the exhauststeam on the opposite side of the larger piston passes outthrough the port, as .20,through the exhaust-cavity in the valve, as 7, down and out through the port or passage, as 18, and aperture, as 182.

.If it should be desired to use live steam only in the smaller cylinder and exhaust-steam in the larger cylinder, the distributing-valve, as 9, is drawn back,'so as to close or shut both the ports, as 17 and 21, from communication with the chamber, as 4. 1f live steam be then ladmitted through the port, as 13, -it will pass into the extreme end of the smaller cylinder through the port, as 15, as before, and the eX- hanst-steam on the opposite side of the piston, as 24, will pass out through the port, as 14, through the exhaust-cavity in the valve, as 11, into the port, as 16, and up through the port, as 162, and through the exhaust-cavity in the valve, as 9, down through the port, as 21, and

-thence through the opening, as 212, into the steam-chamber, as 3; thence through the port, as 19, into the same end of the -larger cylinder, sothat while the live steam is exertingits force against-.the side of the piston, as 24, the exhaust-steam from the opposite end of that cylinder-is exerting its force against,the same side of the larger piston, as 23, both forces operating tomove both pistons in the same direction.

It will thus be seen that when little power is wanted both pistons on the same piston-rod may be operated, the smaller one by live steam andthe larger one by the exhaust-steam from the small cylinder, and that at full stroke as well as when out olf at any point in the stroke, according to the power required; or both cylinders' may be used with live steam and at either full stroke or cut oft' at any point in thestroke, according to the greater degree of power required above that developed by the two cylinders used with live steam and exhaust-steam.

When it is desired to shut oi steam-entirely from both cylinders the distributing-valve, as 9, may be moved into the position shown in dotted lines in Fig. VII, so that the ports,-as`

162, 17 and 21, will communicate, and the airv will then circulate freely through the chambers, as 3 and 4, and steam-passages, and into IOO IIO

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the larger cylinder on both sides of the larger piston, and any back-pressure from partial vacuum created by the pumping7action of the larger piston will be prevented. This is an important feature in my invention, inasmuch `as no inconsiderable annoyance has been ex-v perienced by this action of the pistons in pumping air and creating back-pressure.

Of course it `is not essential that the paseinem 3 4orattached toa sin glerod to actuate bothvalves,

as 7 and l1, simultaneously, and the rod, as 8, may be extended to or be connected with the cab ofthe en gine, so that the distributingvalve, as 9, may be operated therefrom by the engineer,

in any convenient manner, so that no change will be required in the ordinary construction ot' the parts ofthe machinery or valve motion from that now practiced, the only change necessary to the use ofthe invention being that of the cylinder and steam-chest castings.

As applied to a locomotive, the whole arrangement of saddlepiece, as l2, and two cylinders connected therewith may be duplicatedone pair of cylinders on one side the locomotive and another pair on the other side, and the two saddle-pieces bolted together at the flange, as 25, and the boiler fitted and secured to the saddle above this tlange.

Having thus described my invention, what l claim as new is 1. ln an improved compound engine,a chest having two steamchambers arranged side by side and communicating one with the otherby a single port or passage-way controlled by a governing-valve adapted to be operated by the engineer, with the valve-seat in each chamber provided with the ordinary induction and exhaust port/s, controlled in each chamber by a slide-valve, and both moved simultaneously, two cylinders, one of which communicates directly with one of said steam-chambers, and the other cylinder with the other chamber through said induction-ports, and each cylinder containing a piston secured to a single piston-rod com` mon to both, whereby both said pistons may be actuated by live steam at the same time, or one be actuated by live steam and the other by exhaust-steam, substantially as described.

2. ln an improved compound engine, a chest having two steam-chambers arranged side by side and communicating one with the other by a single port or passage-way, in combination with a distributing or governing valve to control said port, and whose actuating-rod extends out through said chest and is adapted to be operated by the engineer, whereby said valve may be moved by the engineer to control the passage of' live steam or of exhauststeam through said port,substantially as described.

3. In an improved compound engine, a chest having two steam-chambers arranged side by side and communicating one with the other by a single port or passagewaycontrolled by a governing-valve adapted to be operated by I the engineer to control the passage of live steam or of exhaust-steam through said port, asaddle-piece having the seats for the valves in said chambers made on its uppersurt'ace and the seat in each chamber provided with induction and exhaust ports, controlled in each chamber by a slide-valve, both moving simultaneously, two cylinders, one made integral HENRY D. DUNBAR.

Witnesses:

T. A. CURTIS, CRAs. H. Woon. 

